... ()7.8 kb to )6.0 kb; DHSs, )7.3 kb and < /b> )6.5 kb);region II, promoter and < /b> upstream region of < /b> Ig -b gene()2.7 kb to +0.05 kb; DHSs, )2.1 kb, )1.0 kb, and< /b> 0 kb); region III, in the first intron of < /b> the ... kb) was determined by < /b> kHindIII. Posi-tions of < /b> the 1.3 kb, 2.7 kb, and < /b> 6.2 kb bands are shown in the rightmargin. (C) Detection of < /b> the extra Ig -b mRNA by < /b> Northern hybridiza-tion. Total RNA ... without Bsr gene. Position of < /b> the probe(0.9 kb; )10.1 kb HindIII to )9.2 kb AccI fragment) for hybridizationis indicated by < /b> a black rectangle. Size and < /b> position of < /b> the HindIIIfragment hybridizable...